A feed device of this type has already become known in which several full material containers are stacked above one another in a magazine. The hollow, cylindrical material containers are open on their front ends and reach a discharge station in a horizontal position with the aid of a lifting device. The discharge station consists of a horizontally slidable discharge piston which, to discharge the material container, enters the hollow, cylindrical interior of the material container from the front end and pushes out the polyester material. The discharge station is placed above the feed cylinder of the injection molding machine so that when the discharge piston pushes through the material container, the material falls into the vertical feed cylinder which is open on the top front side. By lowering the feed ram into the feed cylinder, the material is pressed into the plasticizing cylinder of the injection molding machine.
This known embodiment has the disadvantage that the full material containers are brought in an open state into the feed device. The material containers are of course delivered closed, the covers must nevertheless be removed before the material container is brought into the magazine of the feed device. The result is that the delicate polyester material is exposed, during a relatively long time until being poured into the feed cylinder, to harmful environmental influences, especially air and heat, by which the material properties change. The longer the carrying distance and the dwell time of the open, full material container, the greater is the risk of contamination of the material, especially when light colors are involved. Furthermore, material which remains longer in the machine area requires different machine adjustment parameters than material which stays for a short time, so that a constant change in the control values by the operators is required. This also increases the unpleasant annoyance of odor. The danger exists of material falling out of the open containers and being contaminated. This disadvantage is already noticeable during removal of the covers before bringing the material containers into the magazine of the feed device. The result of this is an increased cleaning expense, which goes even higher the greater the number of machine parts which come or could come into contact with the material.
The object of the invention is thus to keep the time between opening the full material containers and discharging them into the feed cylinder as short as possible and, overall, to simplify and accelerate the feed process.